LAWS OF MOTION

In all the universe, there are few ideas more fundamental than those
expressed in the three laws of motion. Together these explain why it is
relatively difficult to start moving, and then to stop moving; how much
force is needed to start or stop in a given situation; and how one force
relates to another. In their beauty and simplicity, these precepts are
as compelling as a poem, and like the best of poetry, they identify
something that resonates through all of life. The applications of these
three laws are literally endless: from the planets moving through the
cosmos to the first seconds of a car crash to the action that takes
place when a person walks. Indeed, the laws of motion are such a part of
daily life that terms such as inertia, force, and reaction extend into
the realm of metaphor, describing emotional processes as much as
physical ones.

The three laws of motion are fundamental to mechanics, or the study of
bodies in motion. These laws may be stated in a number of ways, assuming
they contain all the components identified by Sir Isaac Newton
(1642-1727). It is on his formulation that the following are based:

The Three Laws of Motion

First law of motion: An object at rest will remain at rest, and an
object in motion will remain in motion, at a constant velocity unless
or until outside forces act upon it.

Second law of motion: The net force acting upon an object is a
product of its mass multiplied by its acceleration.

Third law of motion: When one object exerts a force on another, the
second object exerts on the first a force equal in magnitude but
opposite in direction.